Cleaning pistons and Valves

[79XS11F]

I agree that you can be proud on the job you will have done when you get this bike running. At any age being able to recover an old machine to good running order is a worthwhile endeavor. For me i enjoy the turning of wrenches almost as much as I like riding the finished product. If cash is not a big issue i would take the time to do it right the first time round. If all the parts are with in spec give the cylinders a light hone and go with the new rings. Get the hear sorted out and you will be able to conceder that part of the engine a "done deal" You will not want to do it twice unless your like me and don't mind twisting wrenches. For me there is no time factor because I have 2 other bikes here that I can use.
Rob

[trbig]

the down side to removing the carbon ring is possibly lost oil sealing.

Not trying to argue, but just trying to understand the actual mechanics of how a small buildup of carbon at the absolute TDC of the stroke is going to have anything to do with oil usage. The rings being seated against the piston walls is what holds and seperates the compression in the cylinders and oil in the crankcase. Once that piston moves the tiniest bit, there's no way for that carbon to seal anything and would leave the full brunt of the combustion stroke, as well as the compression stroke to the rings.. as is their job. How is a ring sitting at the top of the cylinder going to help any of this?

I'm not wanting a, "I read once.." Nothing against Rob, I'm just wanting to know HOW it could cause oil consumption by removing this. I will admit that it could be possible for it to help at the instant the combustion starts.. but after maybe 5 degrees and that combustion is still in process.. driving the piston down, how it could make any difference to have a ring of carbon up at the top and how could that have anything to do with your oil rings at the bottom of your piston.

It makes me think that someone did this at one time, then didn't line up the ring gaps correctly, which WOULD cause oil consumption, and blamed the carbon ring... and it stuck.

Tod

[79XS11F]

As I understand it the bottom side of the carbon ridge is a perfect match the the top of the top ring including across the ring gap. So when the piston reaches the top of its stroke the top of the top ring seals against that carbon ridge and prevents blow by of oil that would be being pushed upward during the up stroke. The more wear there is between the piston and the cylinder or the rings and the cylinder, the more oil that will be plowed into the combustion chamber.
Rob

[DGXSER]

Let me be clear that I am not making a statement of anything close to fact, just restating what has been presented. And honestly I can not see what the harm is in leaving the ring, again, especially at the extremely low miles of this engine. So if I were to error, why not let it be on the side of caution and not remove the carbon?

And yes, before you say it, why bother pulling the engine down this far to start with, and why clean the carbon form the piston or the valves. I get that point. in fact, on a standard car engine, I always pull the pistons out the top so you have to remove the ring to get them out. So it must not be the end of the oil seal in a car engine. I fail to see how the bike engine is different in this regard.

[petejw]

As Rob said, the bottom of the carbon build up acts as a seal to prevent oil going pass.

And as Todd said that ring will come back eventually if you do decide to remove it.

IMO id leave it there.

More important is putting the correct pistons and rings in the cylinders they came out of.

[trbig]

Oil doesn't get blown INTO the combustion chamber, so this makes no sense. What that carbon ring is made up of is the microscopic layer of oil that gets burnt on the cylinders after the piston goes down on combustion. When the piston comes back up, it scrapes off this little bit of carbon and pushes it to the top of the cylinder where it gets baked and hardened. That's why it's a perfect fit to the piston and top rings.. that's what pushed it there.

What lets excess oil into the cylinder to get burnt is rings that don't seal very well and aren't wiping the oil clean on the down stroke... leaving too much on the walls to be burnt.

I see no benefit to the carbon ring.. it's just a by-product of the way an internal combustion engine works.


Tod

[petejw]

Not to wanna argue the point Tod, :-)
its the oil thats pushed up on the upstroke
thats left behind on the down stroke that causes the oil ring.

So anyone want to talk about oil or tyres. lol

[tarzan]

Well after all the discussion here I just had to get in on it.It doesnt matter one way or the other in my experience if you remove that ring.If your your just talking about the carbon ring.All it is, is unburnt fuel and oil.Now if there is a step at the top from wear then you have to remove that before you hone or you wont be able to hone the cylinder evenly top to bottom.And that ring is metal and you need to cut it out.

[trbig]

its the oil thats pushed up on the upstroke
thats left behind on the down stroke that causes the oil ring.

I understand that there's some oil left behind, but on the combustion stroke, most of that oil is burnt. Coming back up on the compression stroke after the exhaust stroke, the top ring scrapes the cylinder wall and this carbony/oily residue goes to the top where it's cooked into a nice little hard ring.

So what your saying, is this oil getting scraped up by the top ring, gets to the top where this carbon ring makes a seal. This piston going against this seal with a little oil would be the perfect little hydraulic pump, yet somehow this little ring stops that pressure? Then what? The piston goes back down, that oil would still be sitting on the top ring,(Or left up on the bottom of the carbon ring) then it goes back up and scrapes more along the wall, picks up a little more oil....

As the piston is going up, it's making positive pressure. As a matter of fact, of the four strokes, the only one that creates any negative pressure is the intake stroke. Oil isn't going to blow "up" into an area of positive pressure.. some of which is escaping down past the rings, from a place of much less pressure. The crankcase is somewhat pressurized by the blow-by of the other cylinders, but not more than the inside of the cylinder.

If some are taking me as argumentative, I swear I'm not meaning it that way. I'm just trying to understand how a ring in contact for the slightest millisecond along it's entire stroke could have anything to do with oil consumption. And as stated, most vehicles have the pistons removed out the top of the cylinders and this ring has to be removed.

Can someone use small words and pictures so I can understand?

Tod

[kirmit77]

Wow

i just got home and there is a whole page of argueing about the carbon ring.... well i have something else for you to argue about maybe!

I took off the cover for the stator and.... lets just say its not pretty....

RUST RUST RUST!!! its a bunch of rust and corrosion under there. WHAT TO DO!?!?! it seems to me that this is not any good and i might be having to get some new parts?

also, when removing the gaskets, can i use my angle die grinder with a little buffer wheel that i use to take gaskets off on cars????? or will this hurt the mating surface???

Thanks again

[79XS11F]

i just got home and there is a whole page of argueing about the carbon ring.... well i have something else for you to argue about maybe!

I took off the cover for the stator and.... lets just say its not pretty....

RUST RUST RUST!!! its a bunch of rust and corrosion under there. WHAT TO DO!?!?! it seems to me that this is not any good and i might be having to get some new parts?

also, when removing the gaskets, can i use my angle die grinder with a little buffer wheel that i use to take gaskets off on cars????? or will this hurt the mating surface???

Thanks again

If the O-ring at the front of the starter where it enters the engine has not be breached by water it may look BAD but be confined to the starter alone and starters are pretty easy to come by.
Rob

[kirmit77]

not starter

not the STARTER but the STATOR Im pretty sure thats what you call the magnet with the coil and wires and it connects to the crank shaft on the right side of the engine

[TopCatGr58]

Oh Boy, can I play??

First, Rob,

Put your glasses on...he said STATOR, as in the ALT cover! My Rotor has a nice little layer of rust on it as well. The ALT and charging system on the XS11 is a brushless one, that means that nothing touches against other moving parts. That big rusty ROTOR just spins in between the field coil and the stator coil. So....as long as there's no signs of rubbing on the stator coils or field coils, then you can remove the rust from the ROTOR anyway you want, but a simple wire wheel or brush will be enough.

Now, let me play with the carbon ring theory!

Okay, no actual pressure pushing much oil up past the rings into the combustion chamber. Just a little film of oil left on the cylinder wall as the piston goes up and then back down. Remember, this is going to be on an engine that's already broken in. Oil rings may not seal as well as they should, oil gets by them and also can then slip by the compression rings since they are designed to seal/hold pressure from above and not below! SO..the oil can slip on up past the top rings, but now it hits that carbon ring which is perfectly matched to seal against the piston. The OIL can't get past that carbon ring and seal with the piston, so it's held there.

BUT if the carbon ring is removed, then the oil can more easily slip past the oil and compression rings, and since the carbon ring isn't there to stop it, it gets up into the combustion chamber, gets burned, and continues to CONSUME more oil since it's NOT being stopped by the carbon ring!?

That's my story and I'm sticking to it!
Isn't debating fun!!!
T.C.

[kirmit77]

time for a poll

Everyone should just post one word, DO or DONT as in DO remove the ring or DONT. If i DO remove it then i will hone. If i DONT remove it then the pistons are going in as they are.

try to just use ONE word? and

[79XS11F]

First, Rob,

Put your glasses on...he said STATOR, as in the ALT cover! My Rotor has a nice little layer of rust on it as well. The ALT and charging system on the XS11 is a brushless one, that means that nothing touches against other moving parts. That big rusty ROTOR just spins in between the field coil and the stator coil. So....as long as there's no signs of rubbing on the stator coils or field coils, then you can remove the rust from the ROTOR anyway you want, but a simple wire wheel or brush will be enough.

Now, let me play with the carbon ring theory!

Okay, no actual pressure pushing much oil up past the rings into the combustion chamber. Just a little film of oil left on the cylinder wall as the piston goes up and then back down. Remember, this is going to be on an engine that's already broken in. Oil rings may not seal as well as they should, oil gets by them and also can then slip by the compression rings since they are designed to seal/hold pressure from above and not below! SO..the oil can slip on up past the top rings, but now it hits that carbon ring which is perfectly matched to seal against the piston. The OIL can't get past that carbon ring and seal with the piston, so it's held there.

BUT if the carbon ring is removed, then the oil can more easily slip past the oil and compression rings, and since the carbon ring isn't there to stop it, it gets up into the combustion chamber, gets burned, and continues to CONSUME more oil since it's NOT being stopped by the carbon ring!?

That's my story and I'm sticking to it!
Isn't debating fun!!!
T.C.

I do have my glasses on ... so I will blame the meds :-)
Rob